垃圾焚烧飞灰熔融过程中重金属固化特性

为探索垃圾焚烧飞灰中重金属在熔融过程中的迁移特性,采用燃油式表面熔融炉,对杭州某生活垃圾焚烧厂的焚烧飞灰连续进行了6个多月日处理规模为500kg/d的熔融固化中试实验.采用X射线衍射仪、电感耦合等离子体质谱仪、X射线荧光光谱仪研究不同工艺参数(温度、添加剂、冷却方式)对飞灰中重金属固化率的影响.结果表明:随着温度的升高和添加剂比例的增大,重金属Cu、Zn的固化率显著提高,Pb、Cd和Cr则变化不明显;水冷却方式下,重金属固化率要略大于空气自然冷却.熔融过程中,烟气中常规污染物浓度和二噁英等污染物总毒性浓度均小于标准限值.     

焚烧飞灰熔融特性与熔渣利用技术研究进展

垃圾焚烧飞灰中含有高浸出浓度的Pb,Cd,Cu,Zn等重金属,属于危险废物。高温熔融技术可以有效地控制焚烧飞灰中的重金属污染物。从飞灰无害化和资源化2个角度介绍了熔融技术的研究进展,分析了熔融技术的优缺点,在综述国内外研究成果的基础上,为今后焚烧飞灰的热处理技术提出了研究方向。     

The Cement Solidification of Municipal Solid Waste Incineration Fly Ash

The chemical composition, the content and the leachability of heavy metals in municipal solid waste incineration （ MSWI） fly ash were tested and analyzed. It is shown that the leachability of Pb and Cr exceeds the leaching toxicity standard, and so the MSWI fly ash is considered as hazardous waste and must be solidifled. The effect of solidifying the MSWI fly ash by cement was studied, and it is indicated that the heavy metals can be well immobilized if the mass fraction of the fly ash is appropriate. The heavy metals were immobilized within cement hydration products through either physical fixation, substhtaion, deposition or adsorption mechanisms.     

工业重金属污泥的稳定化试验

以危险废物工业重金属污泥为研究对象,进行了水泥、石灰和石灰 粉煤灰3种稳定化工艺对重金属铅、镉、铬、铜、锌、镍浸出毒性的影响试验,结果表明,水泥稳定化工艺水泥添加量8%、石灰稳定化工艺石灰添加量2%、石灰 粉煤灰稳定化工艺添加量为10%石灰 10%粉煤灰时,均可满足《危险废物填埋污染控制标准》(GB 18598-2001)中关于"危险废物允许进入填埋区的控制限值"的要求.石灰稳定化工艺要求稳定剂的添加量相对较小,是该类工业污泥稳定化处理的理想稳定剂.     

Characteristics of MSWI fly ash during vitrification

The vitrification characteristics of municipal solid waste incinerator (MSWI) fly ash were investigated. Effects of temperature on the binding efficiency of heavy metals, the change of chemical compositions and the weight loss of fly ash in the range of 800-1350 ℃ were studied. Toxicity Characteristic Leaching Procedure (TCLP) of the United States was used to analyze the leaching characteristics of heavy metals in fly ash and molten slag. Results indicate that chemical compositions, the weight loss of fly ash and the binding efficiency of heavy metals in fly ash have a tremendous change in the range of 1150-1260 ℃. The percentage of CaO, SiO2 and Al2O3 increases with the increasing temperature, whereas it is contrary for SO3, K2O, Na2O and Cl; especially when the temperature is 1260 ℃, the percentage of these four elements decreases sharply from 43.72% to 0.71%. The weight loss occurs obviously in the range of 1150-1260 ℃. Heavy metals of Pb and Cd are almost vaporized above 1000 ℃. Cr is not volatile and its binding efficiency can reach 100% below 1000 ℃. Results of TCLP indicate that the heavy metal content of molten slag is beyond stipulated limit values.     

利用热等离子体熔融垃圾焚烧飞灰

为了评价垃圾焚烧飞灰的热等离子体熔融处理效果, 研究SiO2和CaO对重金属固化效果和重金属毒性浸出特性的影响. 在飞灰中添加一定比例的SiO2和CaO, 配置成不同的配灰样品, 利用纯氩热等离子体在1 400～1 500 ℃下, 对飞灰及配灰进行熔融玻璃化的实验研究, 分别利用X射线能量色散谱仪(EDX)、场发射扫描电子显微镜(FSEM)、X射线衍射仪(XRD)和毒性浸出方法(TCLP)分析飞灰和熔渣的化学组成、微观结构、晶相组成和重金属毒性浸出特性. 结果表明, 热等离子体熔融所得熔渣为无定形的玻璃体, 重金属浸出质量浓度均远低于毒性标准. SiO2和CaO的添加都可以改善重金属固化效果, CaO比SiO2对Cu、Zn、Cd和Pb挥发的抑制效果更好. SiO2的添加可以改善熔渣中重金属的浸出特性, 而CaO的作用与之相反.     

Solidification/Adsorption of Heavy Metals by FA/FA-MSWI based Al-Substituted Tobermorite

Fly ash(FA) was utilized to hydrothermally synthesize FA based Al-substituted tobermorites, and was combined with raw materials of FA and municipal solid waste incineration fly ash(MSWI) to hydrothermally synthesize FA-MSWI based Al-substituted tobermorites. Then optimum samples named FA-T and FM-T were selected, correspondingly. Their intrinsic properties as well as their solidification/stabilization and adsorption of heavy metals were studied. The experimental results showed that the specific surface area of FA-T and FM-T was 28.259 m~2/g and 45.939 m~2/g, respectively. Their pore size distribution, particle size distribution, and median particle size were approximately the same. FA-T and FM-T both had great potential of solidification/stabilization heavy metal to dispose hazardous solid waste. Further, FA-T and FM-T also showed good adsorption efficiency for heavy metals Pb~(2+) and Cu~(2+) as adsorbent to treat waste water.     

Microstructures and thermal properties of municipal solid waste incineration fly ash

To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration (MSWI) fly ash were studied by measuring the chemical element composition, specific surface area, pore sizes, functional groups, TEM image, mineralogy and DSC-TG curves of raw and sintered fly ash specimens. The results show that MSWI fly ash particles mostly have irregular shapes and non-typical pore structure, and the supersonic treatment improves the pore structure; MSWI fly ash consists of such crystals as SiO₂, CaSO₄ and silica-aluminates, and some soluble salts like KCl and NaCl. During the sintering process, mineralogy changes largely and novel solid solutions are produced gradually with the rise of temperature. Therefore, the utilization of a proper thermal technology not only destructs those persistent organic toxicants but also stabilizes hazardous heavy metals in MSWI fly ash.     

生活垃圾焚烧飞灰重金属特性分析

对国内四个不同的垃圾焚烧厂产生的飞灰进行物理及化学特性分析.四种飞灰在颗粒尺寸分布上有相似的规律,飞灰中重金属的质量分数分析结果表明采用纯垃圾焚烧的炉排炉飞灰中的质量分数高于掺煤混烧的流化床焚烧飞灰中的质量分数.随着飞灰颗粒尺寸的减小,飞灰中重金属的浓度呈现增加的趋势.飞灰的渗滤特性表明,飞灰中Ca质量分数越高,飞灰的酸中合能力越强,且重金属的渗出率受飞灰渗滤液的pH影响大,而在碱性渗滤条件下受飞灰中重金属质量分数的影响小.     

矿山充填复垦场地重金属含量对比研究

为保证矿山充填复垦场地作为农用地的生态安全性，通过对现场不同深度土壤、小麦根系采样分析，研究了粉煤灰和煤矸石两种不同物料充填复垦场地中As，Hg，Pb，Cu，Cd，Cr，Zn等重金属的含量，并与当地对照土壤比较．结果表明：粉煤灰中Pb，Cu含量高于比照土壤，矸石中Cu，Zn含量高于比照土壤，但是充填复垦场地覆土土层0～20cm厚度内，除了矸石充填场地Zn明显高于比照土壤外，其他元素含量均无明显差异，覆土土层40cm厚度处，矸石充填场地Cu，Zn含量明显高于比照土壤；而充填复垦场地作物根系中的重金属含量与对照场地不存在明显差异，矸石与粉煤灰中重金属的含量与作物根系的重金属含量并不成正比．     

矿区充填复垦土壤重金属分布特征研究

为保证矿区种植农作物的充填复垦土地的生态安全,以徐州柳新矿区粉煤灰、煤矸石充填以及对照场地为研究区,通过对3块场地中As,Cd,Cr,Cu,Hg,Pb,Zn 7种重金属元素不同深度含量分析,总结7种重金属纵向的分布情况,并将3块场地重金属含量与土壤背景值、土壤环境质量标准做比较,分析7种重金属元素的变化度和污染程度.结果表明:3块场地中,相对于土壤背景值,Hg,Cu,Cd,Pb的变化度均较大;煤矸石场地的Zn变化度偏大;As,Cr的变化度均较小.相对于土壤质量评价标准,Cd均超过土壤质量标准;除极少数As,Zn,Cu样点超标,其余均未超标.在此基础上,对Cd进行详细分析,以粉煤灰场地为例,建立了Cd纵向分布的克里格模型,所建模型拟合精度较高.研究结果将为矿区污染土地的修复并进而制定相应治理措施提供依据.     

废弃粗粉煤灰-水泥系统固化重金属废弃物的探讨

利用强度发展、毒性浸出试验(TCLP)和动态浸出试验(DLT)等手段探讨了废弃粗粉煤灰-水泥系统固化/稳定含铅、铜和锌的重金属废弃物的可能性。研究发现废弃粗粉煤灰-水泥系统养护28d后符合固化/稳定的指标要求，而且长期效果优于细粉煤灰-水泥系统。另外试验还发现，固化/稳定系统的酸中和能力是决定样品中重金属浸出能力的主要指标。     

垃圾焚烧飞灰处理高浓度含磷废水的动力学

采用能谱分析（EDS）,荧光光谱分析（XRF）,透射电子显微镜（TEM）测试的手段结合水化学理论研究了垃圾焚烧（MSWI）飞灰去除废水中高浓度磷酸盐的动力学。结果表明：MSWI飞灰除磷速率较快,303K下30min磷去除率95％;除磷过程宏观表现为吸热过程,但对外加能量要求较低;除磷反应对MSWI飞灰中的重金属有很好的稳定化效果,反应后溶液中重金属未检出。化学沉淀是MSWI飞灰除磷的主要机制,Ca、Fe、Zn等均可为反应提供阳离子。反应物PO。”与可溶性产物的内扩散过程是飞灰除磷的控制步骤,宏观动力学过程适用于球体内扩散控制模型,磷酸盐反应率与时间的关系可描述为1—3（1-x）^2/3＋2X—kt,实验得到表观活化能约10．06kJ／mol。     

Synthesis and heavy metal immobilization behaviors of fly ash based gepolymer

Two aspects of studies were carried out: 1) synthesis of geopolymer by using fly ash and metakaolin; 2) Immobilization behaviors of fly ash based geopolymer in a presence of Pb and Cu ions. As for the synthesis of fly ash based geopolymer, 4 different fly ash content (10%, 30%, 50%, 70%) and 3 types of curing regimes (standard curing, steam curing and autoclave curing) were investigated to obtain the optimum synthesis condition based on the compressive and flexural strength. The experimental results show that geopolymer, containing 30% fly ash and synthesized at steam curing (80° for 8 h), exhibits higher mechanical strengths. The compressive and flexural strengths of fly ash based geopolymer reach 32.2 MPa and 7.15 MPa, respectively. Additionally, Infrared (IR) and X-ray diffraction (XRD) techniques were used to characterize the microstructure of the fly ash geopolymer. IR spectra shows that the absorptive band at 1086 cm⁻¹ shifts to lower wave number around 1033 cm⁻¹, and the 6-coordinated Al transforms into 4-coordination during the synthesis of fly ash based geopolymer. The resulting geopolymeric products were X-ray amorphous materials. As for immobilization of heavy metals, the leaching tests were employed to investigate the immobilization behaviors of the fly ash based geopolymer synthesized under the above optimum condition. The leaching tests showed that fly ash based geopolymer can effectively immobilize Cu and Pb heavy metal ions, and the immobilization efficiency reached 90% greater when heavy metals were incorporated in the fly ash geopolymer in the range of 0.1% to 0.3%. The Pb exhibits better immobilization efficiency than the Cu, especially in the case of large dosages of heavy metals.     

Solidification of Municipal Solid Waste Incineration Fly Ash with Cement and Its Leaching Behaviors of Heavy Metals

The solidifying qffect of cement addition on municipal solid waste incineration fly ash ( MSWFA for short, collected from the gas exhaust system of MSW incinerator), the interaction of MSWFA with cement and water and the leaching of heavy metals from cement-solidified MSWFA are investigated. The main results show that : ( 1 ) when MSWFA is mixed with cement and water, 112 evolution, the formation and volume expansion of AFt will take place, the volume expansion can be reduced by ground rice husk ash addition ; (2) heavy metals do leach from cement-solidified MSWFA and at lower pH more leaching will occur; (3) compared with cement - so-lidified fly ash, the leachate of solidified MSWFA is with higher heavy metal contents ; (4) with the increment of cement addition leached heavy metals are decreased ; and (5) concentrations of Zn , Mn , Cu and Cd in all the leachates can meet the relevant Standards of Japan, but as the regulations for soil and groundwater protection of Japan are concerned, precautions against the leaching of Pb , Cl^- and Cr^6 and so on are needed.     

粉煤灰改性及钝化污泥实验研究

以粉煤灰和石灰石为原料,加入一定量矿化剂,在微波辐照下进行改性,得到吸附材料粉煤灰沸石（FZ）,通过X射线衍射和电镜扫描等方式对粉煤灰辐照改性原理及产物结构等进行了分析,通过添加不同比例的粉煤灰对城市污泥进行了钝化实验研究,并对钝化作用机理进行了分析,对钝化污泥中重金属含量变化及养分含量进行了测试,实验结果表明,改性粉煤灰对污泥中含重金属Zn、Cu、Mn具有明显钝化作用,对污泥中养分具有良好的滞留效果,经钝化处理后,污泥中重金属Zn、Cu、Mn含量都显著低于国家农用标准,污泥渗滤液中全氮含量低于中国地面水环境质量标准（10mg·L^-1）,全磷含量低于污水排入城市下水道水质标准（1mg·L^-1）。     

Effect of MSWI fly ash and incineration residues on cement performances

The activities of municipal solid waste incineration (MSWI) fly ash and incineration residues were studied contrastively, through the component analysis and the activity ratio tests. The mechanical properties, hydration mechanism and leaching toxicity of the hardened cement paste mixing with MSWI fly ash and incineration residues were investigated. The experimental results indicated that the active constituents (CaO+Al₂O₃+Fe₂O₃) in MSWI fly ash were higher than those in incineration residues. Therefore the activity ratio of MSWI fly ash was 43.58%, twice as much as that of incineration residues. Meanwhile, the hydration of cement was delayed by mixing with MSWI fly ash and incineration residues, which also reduced the cement strength markedly. By adding with exceeding 20% MSWI fly ash, the specimens expanded and microcracks appeared. The leaching toxicities of cement pasted mixed with MSWI fly ash and incineration residues were lower than the Chinese national standard. Accordingly the cement mixed by MSWI fly ash and incineration residues can be considered as the environment-friendly materials.     

高钙粉煤灰地聚合物固化/稳定重金属的试验研究

利用高钙粉煤灰研制地聚合物来固化/稳定重金属,采用静态和动态浸出试验研究了高钙粉煤灰地聚合物对重金属的固化/稳定效果,并进一步探索了重金属的迁移机制和长期安全性.研究表明:高钙粉煤灰地聚合物分别固化/稳定0.025％的铅,0.025％的铬和0.01％的汞后,经静态浸出试验,重金属浸出浓度远低于规定的上限值,且固化率均在98％以上.经动态浸出试验,重金属的实时浸出浓度低于规定的上限值,累积浸出浓度在72 h后趋于稳定;固化体中重金属的径向分布相似;重金属的有效扩散系数和浸出率非常低,长期安全性优良.     

Solidification Efficiency and Mechanism of Conventional Curing Agents for Sewage Sludge Stabilization and Dewatering

One of the challenges faced by sewage sludge treatment and disposal is its higher water content, and how to efficient dewater those hazardous materials properly is welcome in practice. This study stabilized the sewage sludge via the using of conventional curing agents and calcined aluminum salts, and the corresponding dewatering mechanisms and structural changes of the stabilized sludge were further comparable analyzed. Experimental results showed that wollastonite and kaolin exhibit a relative higher dewatering efficiency as compared to other conventional curing agents; however the releasing rate of heavy metals of Cu, Cr, Ni for kaolin solidification and Zn, Pb for wollastonite solidification is higher than the sludge samples solidified by other curing agents. For comparison, the sludge samples solidified by calcined aluminum salts (AS), calcium ash, Mg-based curing agent, tricalcium aluminate (C₃A) show a lower heavy metals leaching potential and unconfined compressive strength. In addition, the economic characteristics and local availability of AS, calcium ash, C₃A and CaO makes it have a broad prospect in extension and application. These findings are of great significance for stabilization and dewatering of sewage sludge.     

用于水污染重金属检测的微电极阵列传感器芯片

基于溶出伏安法,采用一种新型的汞膜金微电极阵列传感器芯片,实现了水污染痕量重金属离子Zn2+、Cd2+、Pb2+和Cu2+的同时检测.在K3［Fe(CN)6］溶液中对微电极阵列传感器进行循环伏安扫描,分析其电化学特性及实际表面积,采用电化学阻抗谱法检验微电极阵列传感器表面汞膜沉积的程度.镀汞后的微电极阵列传感器采用差分脉冲阳极溶出伏安法,同时检测样本溶液中的重金属元素:Zn2+、Cd2+、Pb2+和Cu2+,得到的Cd2+、Pb2+和Cu2+的标准工作曲线线性度良好,检测下限分别为0.1、0.5和0.3 μg/L,但Zn2+的标准工作曲线线性度较差,这主要是由测试基线的漂移及不准确的加标造成的.